I'd like to share with you guys how to build a watertight compartment. The solution you'll see, has tested tight at 2.5 bar (Both compartment and internal hose system), that's the pressure at 82 ft. Surf to http://hjem.get2net.dk/robse/pages/SSBN/SSBN.htm , and look under "My Results", "WTC1" and "WTC2"

Thank you for detailing the construction in your website. Very educational !

As an observation from partially looking through the rest of the site, I saw you use a mechanical device to level the ship. Did you put in some PD (proportional-differential) circuit ? otherwise you risk that the boat in correcting the previous error, creates the next one. (this is called overshoot, and leads to the boat never getting level but porpoising) Given you technical expertise, I assume you have given this a thought.

EXELENT point!!! ...and you're right: I have cought this problem on the drawing board a while back. The system has a delay of about 7 sec's to avoid it fighting it self, or waves for that matter..I'm impressed that you cought this problem at first glimse... it took me a week to think of that one... wow.

I am building my first WTC from scratch. I have the 3" plexiglas tube cut and the end-caps made. Next step is to make the tray for the interior electronics, servos, motor, gearbox, etc. I have noticed that some folks place their gear box on the wet side of the WTC end-cap. This would save space of course. I am planning to build mine inside. But here is my real question: Do most of you place the main battery in the wet space?? I know gel-cells are ok for this. What about the 6-cell 7.2volt ni cd battery packs?? Will they perform ok in the wet space?